Method of extracting bromin.



A. E. SCHAEFER. METHOD OF EXTRACTING BROWN.- APPLICATION F!LED AUG-1,1910.

Patgntd June 27, 1916.

sratrns earner option.

ARTHUR E. SCHAEFER, OF MIDLAND, MICHIGAN, ASSIGNOR TO THE DOW CHEMICAL COMPANY, OF MIDLAND, MICHIGAN, A CORPORATION OF MICHIGAN.

METHOD or EXTRACTING BRoMIN.

Specification of Letters Patent.

Patented June 27, 19116.

Application filed August 1, 1910. Serial N 0. 574,908.

To all whom it may concern Be it known that I, ARTHUR E. SoI-IAErEn, a citizen of the United States, and a resident of Midland, county of Midland, 'anda State of Michigan, have invented a new and useful Improvement in Methods of Extracting Bromin, of which the following is a. specification, the principle of the invention being herein explained and the best mode in which I have contemplated applying that principle, so as todistinguish it from other inventions.

My invention, relating as indicated to a process for extracting bromin from brine, has regard more particularly to certain improvements in the general process explained and claimed in U. S. Letters Patent No. 714,160 issued to Herbert H. Dow, November 25, 1902.

The object of the invention is the more complete, as well as more economical extraction of the bromin from the natural bromid-containing brines that here, as in such general process, form the basis of the operations of steps constituting the process. Such steps will be hereinafter fully described and particularly pointed out in claims.

The annexed drawing and the following description set forth in detail one mode of carrying out the invention, such disclosed mode, however, constituting but one of "a- -rious Ways in which the principle of the inof such system are supplied, as also the reservoir A of the main system.

The detailed construction of the respective systems and of their inter-connection, may be readily explained by reference to the drawing. The brine from reservoir A of the main system is permitted to flow by way of a pipe (L into an oxidizer A where oxidation of the brine may be accomplished in any approved fashion, as by one of the 1 various means explained in U. S. Letters the brine received by reservoir A from the auxiliary system, a' portion of brine is bypassed through a pipe 6?. through a purity ing tower A which is a tower similar in construction to the blow-out tower, and one in which the oppositely flowing gas may be brought into intimate contact with the brine as it passes therethrough. From the purifier A the brine is pumped through pipe a a into the oxidizer A previously referred to.

A gas connection a is provided in the main system leading from the top of tower A to the bottom of the purifier A a branch 0. from the oxidizer A being joined to such connection at an intermediate point. From the purifier the gas is carried through a duct (4 to a second purifier A and thence by a duct a to an absorber A 7 A strong bromid solution, provided fromany suitable source, such as a receptacle a fis caused to circulate through such second purifier, while a proper absorbent solution 'for combining with bromin such as a water solution of soda ash, provided from any suitable source, such as a receptacle (1, is similarly caused to circulate through the absorber A Connected with absorber A is an exhaust blower C that exhausts directly into the atmosphere. By means of such blower a current of air, laden of course with gases given olf in certain parts of the apparatus just de scribed, is drawn through not only the main duct 6 leading from said blow-out tower enters the base of an absorption tower B likewise forming part of the auxiliary system, it ,being through this tower and pipes b and b that the brine passes on its way from brine reservoir B to brine reservoir A. It is from the top of said absorption tower that the duct 6 to the bottom of the blowout tower of the main system leads.

In describing in detail how my improved process is carried out attention will first be given to the flow of'the brine through the foregoing apparatus. The unoxidized brine from the reservoir B of the auxiliary system passes down over the secondary absorp- .tion tower B Where it is preliminarily oxi dized by the chlorin and bromin gas from .the blow out tower B Such oxidizing step will hereinafter be referred to as the prelimlnary oxldation, and results in oxldizing the-ferrous salts and other reducing compounds such as exlst-ln natural brines. In

t order toefi'ect a practically complete oxidation ofthese reducing compounds, I find it of practical dimensions, to blow out from necessary, when using an absorption tower the tower B an excess of free chlorin and b'romin, over and above that actually rei 'quired to oxidize the reducing compounds in the brine. This excess passes on and is absorbed in the main system, as will be subse- .the bromin is freed. be simultaneously and of necessity, a large portion of chlorin set free. From such oxiquently described. The portion of the brine thus freed from the reducing compounds passes from the tower B into the reservoir A of the main system and thence into the primary oxidizing tower A forming a part of such system. Another portion of the brine passes directly'tothe brine purifying tower A by a branch I) in the pipe I) that leads directly to reservoir A. From tower A the brine is, however, pumped to the oxidizer A so that eventually all the brine passes through the latter. In such oxidizer the brine is designed to be oxidized shortof its bromin content, so that most of the bromin is free, there being at the same time some chlorin set free.

The oxidized brine next passes through the blow-out tower A where most of the free halogen is removed. Thence the brine is pumped to the secondary oxidizer B of the auxiliary system, in which oxidizer it is designed to be oxidized in excess of its bromin content, so that practically all 'of There will, of course,

dizing tower the brine passes over secondary 'blow-out tower 13 where substantially all of the bromin is removed, the brine then flow- .ing towaste, or being utilized for the pro-.

duction of products bromin compounds.

While the foregoing description has in part traced the flow of the gas, as wellas other than bromin or that of the brine through the main and auxiliary systems of the apparatus, theflow of the gas, wholly induced as previously indi cated, by suction, maybe more particularly noted. The fresh air enters the apparatus at the bottom of the secondary blow-out tower B removing the free halogen from thebrine passing down over this tower, so that upon emerging from the top of the tower the gaseous mixture contains bromin, as well as a large proportion of chlorin. The larger portion of these halogens is then absorbed, as the gas passes through the tower B the chlorinbyfreason of its greater chemical afiinity being more completely absorbed than the bromin, this chlorination and bromination effecting the preliminary oxidation of the brine, any excess of halogen, such as has been explained isdesirable, passing on through connection 6 into blow-out tower A of the main system. Here most of the chlorin in the entering gas is converted by substitution into bromin by the unoxidized b-romids in the brine flowing down over the tower. Simultaneously the halogens, which have been freed in the brine in oxidizer A are blown out. Accordingly the gas emerging from tower A contains a large proportion of bromin and a small proportion of chlorin. From said tower it passes through duct or .to the brine purifying tower A absorbed in some suitable material and thus converted into bromids. The brominated air passes out into the atmosphere through the exhaust blower C.

This improved method possesses'a number of advantages, among which may be mentioned the fact that it prevents the loss of the excess of chlorin and bromin gas not absorbed in the secondary absorption tower B which gas would pass into the atmosphere in the process described in said Patent No. 714,160. The greater part of the chlorin in the air entering tower B replaces the bromin in the brine. Consequently, but

very little. chlorin gas goes into the mainsystem, the slight amount being practically negligible so far as any appreciable disadvantage to the efliciency of the operation is concerned, while the relatively high temperature of the air materially assists in the rapid vaporization of the bromin.

Still another advantage of .very considerable consequence resides in the fact that by the improved process herein described, the air that is used to blow out the bromin in the primary tower has already been warmed cold air, the passage of such warm brominladen air through the. purifying tower and absorption tower may be made slower, and consequently, the absorption and extraction rendered more thorough. This advantage becomes the more striking in the winter time when the air is much cooler than the brine, since 111 such case the cooling effect of the large volume of cold air required by the process described in Patent No. 714,160 makes it diiiicult to blow out the bromin.

It will he, of course, understood in connection with the preceding description of the process and of apparatus suitable for carrying on the same, that instead of oxidizing the bromin in two steps as described, the oxidation may be carried on in more than two steps and that correspondingly the blowing out of the halogens may be done in a like number of successive steps without in any way interfering with the principle of my invention. Similarly, while but a single blowing-out tower, purifying tower, etc., is shown, it will be evident that such tower in each instance may be replaced by two or more towers Without in any way affecting the operation. So, moreover, for practical considerations, it is proposed to use atmospheric air for blowing out the halogens in the blow-out towers of the main and auxiliary systems respectively, but any inert gaseous diluent, such for example as spent furnace gases after purification involving the removal of the carbon dioxid, sulfur, etc., included therein, may be used in place of such air, as need not be exp'lained in de tail.

Other modes of applying the principle of my invention may be employed, instead of the one explained, change being made as regards the process herein disclosed, provided the step or steps stated by any of the following claims or the equivalent of such.

stated stepor steps be employed.

I therefore particularly point out and distinctly claim as my invention-:.

1. In a process of extracting bromin from bromid-containing brine, the steps which consist in oxidizing a portion of such brine short of its bromin content, blowing out the bromin liberated thereby with chlorin containing gas, and simultaneously producing such gas by further oxidation and blowing of another portion of such brine.

2. In a process of extracting bromin from I bromid-containing brine, the steps which consist in oxidizing a portion of such brine short of its bromin content, blowing out the bromin liberated thereby with chlorin containing gas, and simultaneously producing such gas by further oxidation and blowing of another portion of such brine.

3. In a process of extracting bromin from bromid-containing. brine, the steps which consist in preliminarily oxidizing such brine, next oxidizing such brine short of its bromin content, and then blowing such brine with free halogen.

4. In a process of extracting bromin from bromidcontaining brine, the steps which consist in oxidizing such brine, to oxidize the reducing compounds therein, next oxidizing such brine short of its bromin content, and then blowing such brine with free chlorin.

5. In a process of extracting bromin from bromid-containing brine, the steps which consist in bringing such brine into contact with free halogen in excess of that required to eifect a preliminary oxidation of such brine, thereby producing free halogen, oxidizing such brine short of its bromin con tent; and then blowing such brine with the excess of such free halogen from such first step. i

6. In a process of extracting bromin from bromid-containing brine, the steps which consist in bringing such brine into' contact with free chlorin in excess of that required to effect a preliminary oxidation, oxidizing the brine so treated short of its bromin con 'tent; and then blowing such oxidized brine bromid-containing brine, the step which consists in almost completely removing the bromin from such brine by blowing it, after the first liberation of halogen by oxidation, with a halogen-containing gas derived from a subsequent liberation of halogen by oxidation.

9. In a process of extracting bromin from bromid-containing brine, the step which consists in almost completely removing the bromin from such brine by blowing it, after the first liberation of halogen by oxidation, with a chlorin-containing gas derived from a subsequent liberation of halogen by oxidation.

10. In a process of extracting bromin from bromid containing brine, the steps which consist in passing a current of air in succession through such brine after having been oxi ized in excess of its bromin content, then through such brine in its original state to eifect its preliminary oxidation, and finally through such brine after it has been oxidized short of its bromin content.

11. In a process of extracting bromin from bromidcontaining brine, the steps which consist in preliminarily oxidizing such brine; next oxidizing it short of its bromin content; then oxidizing it in excess of such content, and passing a current of air in succession through such brine in its third, first and second stages of oxidation in the order named.

12. In a process of extracting bromin from bromid-containing brine, the steps which consist in blowing a brine which has been oxidized short of itsbromin content, thereby bringing the air to substantially the temperature of the brine, and blowing such warmed air over a brine relatively rich in bromin.

13. In a process of extracting bromin from bromid-containing brine, the steps Which consist in blowing a.brine which has been oxidized short of its bromin content, thereby bringing the air to substantially the temperature of the brine, removing a part of the chlorin carried from said brine by said warmed air, and then blowing said air over a brine relatively rich in bromin.

14. In a process of extracting bromin from brine containing bromid, the steps which consist in bringing'a current of air into contact With such brine, after oxidation in excess of its'bromin content, then into contact With such brine in its natural state to effect a preliminary oxidation; then into contact with such brine after oxidation short of its bromin content, and then oxidizing said brine in excess of its bromin content for treatment in said first step.

Signed by me this 23rd day of July, 1910.

ARTHUR E. SCHAEFER. Attestcd by 7 G. LEE CAMP,

THos. GRIsWoLD, Jr; 

